Merge tag 'xtensa-20221010' of https://github.com/jcmvbkbc/linux-xtensa

Pull xtensa updates from Max Filippov:

 - add support for FDPIC and static PIE executable formats for noMMU

* tag 'xtensa-20221010' of https://github.com/jcmvbkbc/linux-xtensa:
  xtensa: add FDPIC and static PIE support for noMMU
  xtensa: clean up ELF_PLAT_INIT macro

4 files changed, 28 insertions, 5 deletions

diff --git a/arch/xtensa/include/asm/elf.h b/arch/xtensa/include/asm/elf.h
index 909a6ab4f22b..ffcf1ada19c6 100644
--- a/arch/xtensa/include/asm/elf.h
+++ b/arch/xtensa/include/asm/elf.h
@@ -93,6 +93,10 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
 #define elf_check_arch(x) ( ( (x)->e_machine == EM_XTENSA )  || \
 			    ( (x)->e_machine == EM_XTENSA_OLD ) )
 
+#define ELFOSABI_XTENSA_FDPIC 65
+#define elf_check_fdpic(x) ((x)->e_ident[EI_OSABI] == ELFOSABI_XTENSA_FDPIC)
+#define ELF_FDPIC_CORE_EFLAGS 0
+
 /*
  * These are used to set parameters in the core dumps.
  */
@@ -153,10 +157,22 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
  */
 
 #define ELF_PLAT_INIT(_r, load_addr) \
-	do { _r->areg[0]=0; /*_r->areg[1]=0;*/ _r->areg[2]=0;  _r->areg[3]=0;  \
-	     _r->areg[4]=0;  _r->areg[5]=0;    _r->areg[6]=0;  _r->areg[7]=0;  \
-	     _r->areg[8]=0;  _r->areg[9]=0;    _r->areg[10]=0; _r->areg[11]=0; \
-	     _r->areg[12]=0; _r->areg[13]=0;   _r->areg[14]=0; _r->areg[15]=0; \
+	do { \
+		(_r)->areg[0]  = 0; /*(_r)->areg[1] = 0;*/ \
+		(_r)->areg[2]  = 0; (_r)->areg[3]  = 0; \
+		(_r)->areg[4]  = 0; (_r)->areg[5]  = 0; \
+		(_r)->areg[6]  = 0; (_r)->areg[7]  = 0; \
+		(_r)->areg[8]  = 0; (_r)->areg[9]  = 0; \
+		(_r)->areg[10] = 0; (_r)->areg[11] = 0; \
+		(_r)->areg[12] = 0; (_r)->areg[13] = 0; \
+		(_r)->areg[14] = 0; (_r)->areg[15] = 0; \
+	} while (0)
+
+#define ELF_FDPIC_PLAT_INIT(_r, _exec_map_addr, _interp_map_addr, dynamic_addr) \
+	do { \
+		(_r)->areg[4] = _exec_map_addr; \
+		(_r)->areg[5] = _interp_map_addr; \
+		(_r)->areg[6] = dynamic_addr; \
 	} while (0)
 
 typedef struct {
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index 76bc63127c66..b75ba16ec080 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -205,9 +205,12 @@ struct thread_struct {
 #define start_thread(regs, new_pc, new_sp) \
 	do { \
 		unsigned long syscall = (regs)->syscall; \
+		unsigned long current_aregs[16]; \
+		memcpy(current_aregs, (regs)->areg, sizeof(current_aregs)); \
 		memset((regs), 0, sizeof(*(regs))); \
 		(regs)->pc = (new_pc); \
 		(regs)->ps = USER_PS_VALUE; \
+		memcpy((regs)->areg, current_aregs, sizeof(current_aregs)); \
 		(regs)->areg[1] = (new_sp); \
 		(regs)->areg[0] = 0; \
 		(regs)->wmask = 1; \
diff --git a/arch/xtensa/include/uapi/asm/ptrace.h b/arch/xtensa/include/uapi/asm/ptrace.h
index 50db3e0a6341..9115e86ebc75 100644
--- a/arch/xtensa/include/uapi/asm/ptrace.h
+++ b/arch/xtensa/include/uapi/asm/ptrace.h
@@ -37,6 +37,10 @@
 #define PTRACE_SETXTREGS	19
 #define PTRACE_GETHBPREGS	20
 #define PTRACE_SETHBPREGS	21
+#define PTRACE_GETFDPIC		22
+
+#define PTRACE_GETFDPIC_EXEC	0
+#define PTRACE_GETFDPIC_INTERP	1
 
 #ifndef __ASSEMBLY__
 
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index f14478643b91..93539aac0e5b 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -58,7 +58,7 @@ config ARCH_USE_GNU_PROPERTY
 config BINFMT_ELF_FDPIC
 	bool "Kernel support for FDPIC ELF binaries"
 	default y if !BINFMT_ELF
-	depends on ARM || ((M68K || SUPERH) && !MMU)
+	depends on ARM || ((M68K || SUPERH || XTENSA) && !MMU)
 	select ELFCORE
 	help
 	  ELF FDPIC binaries are based on ELF, but allow the individual load